This invention relates to shut-off valves for fluid flow conduits and, more particularly, to shock actuated, shut-off valves for such conduits. Although the shut-off valves described herein are particularly well adapted for closing natural gas lines in response to vibratory forces arising from seismic disturbances, their use is not so limited and they may be used to interrupt flow in lines carrying different kinds of gases and fluids under wide ranges of temperature and pressure in response to shock actuation from diverse sources.
In an earthquake or seismic disturbance of any significant magnitude, substantial vibratory forces are generated which can damage and rupture feeder lines used to deliver natural gas into residential, commercial and public structures. As a result, natural gas can leak or flow from such damaged or ruptured lines and accumulate in and about the aforesaid structures. The accumulated natural gas can form an explosive mixture with the surrounding air and be detonated by an appliance pilot light, other fire source or a spark. The fire and explosion hazard from damaged or broken gas lines following an earthquake is well known and constitutes a significant threat to persons and property.
A number of shock actuated, gas shut-off valves have been disclosed in the prior art to meet the fire and explosion hazard posed by earthquake damage to gas feeder lines. These prior art disclosures include U.S. Pat. No. 2,585,316 (Hobson, 1952); U.S. Pat. No. 2,927,592 (Ferre, 1960); U.S. Pat. No. 3,747,616 (Lloyd, 1973); and U.S. Pat. No. 3,768,497 (Mueller, 1973).